Autism is the most costly medical condition in Britain, say researchers.

It costs the UK £32 billion a year - more than heart disease, cancer and stroke combined.

Researchers at the London School of Economics and Political Science (LSE) have produced the most comprehensive estimate yet of treatment, lost earnings, care and support costs for children and adults with autism.

Autism, or autistic spectrum disorder (ASD), including Asperger’s syndrome, is an umbrella term for a range of developmental disorders that have a lifelong effect on someone’s ability to interact socially and communicate.

An estimated 600,000 children and adults in the UK are affected by ASD and genetic factors play a role in its development.

A quarter of people with autism are unable to talk, and 85 per cent do not work full time.

New research, published in the Journal of the American Medical Association Pediatrics, concluded the financial costs of autism in the UK were much higher than previously estimated.

The overall cost of autism to the UK economy is £32.1bn per year, compared to cancer (£12bn) heart disease (£8bn) and stroke (£5bn).

The study found the cost of supporting someone with autism who did not have intellectual disabilities was £0.92 million.

The cost rose to £1.5 million for an individual with autism who is also intellectually impaired.

The largest costs during childhood are special education and lost earnings by parents.

Among adults with autism, the highest costs were for residential or special living facilities and lifetime loss of earnings by the affected individual.

The figures also show Britain spends just £4m per year on autism research, compared to cancer (£590m) heart disease (£169m) or stroke (£32m).

Professor Martin Knapp from LSE, who led researchers from the UK and US, said between 40 and 60 per cent of people with autism spectrum disorders also have intellectual disabilities.

He said ‘What these figures show is a clear need for more effective interventions to treat autism, ideally in early life, making the best use of scarce resources,.

‘New government policies are also needed to address the enormous impact on families.’

Christine Swabey, CEO of Autistica, the UK’s leading autism research charity, said ‘We care about the human stories behind these numbers. Autism is life long and can make independent living and employment hugely challenging. This is part of why it has a greater economic impact than other conditions.

‘There is an unacceptable imbalance between the high cost of autism and the amount we spend each year on researching how to fundamentally change the outlook for people.

‘We know that progress is possible. The right research would provide early interventions, better mental health, and more independence. But right now we spend just £180 on research for every £1million we spend on care.’

Autism researcher Professor Declan Murphy, from the Institute of Psychiatry, said ‘The cost figures show that autism affects all of us in society, every day, regardless of whether or not we have a family member or friend with autism.

‘So we all need to play a part in making things better. More research funding would mean that we could conduct studies to transform lives.’

In a recent survey by Autistica, 90 per cent of parents and 89 per cent of adults with autism said that there was a need for greater scientific understanding of autism.

One father said ‘We should be making science work harder to make life more bearable.’

A woman, who was diagnosed with autism aged 50, said ‘I look for interventions, but there do not seem to be interventions for people my age.’